How to estimate in advance the behavior of the model? Usually indicates the need to monitor wing loading. But this works only for comparisons approximately equal sized models.
In the Czech magazine RC Revue 6/2011 was an interesting article dealing with the 3D wing loading. For a long time, I wondered how to use the wing surface load, when that interpretation depend on the size of the model.
For myself, I came up with a similar indicator (wing loading) / wingspan.
I did not know that there is already a recognized indicator that works.
WL = m / S
WCL = WL / sqrt (S)
m ... Model Weight [g] or [oz]
S ... Wing Area [square dm] or [square ft]
WL ... Wing Surface Load [g/square dm] or [oz/square ft]
WCL ... Wing Cube Loading [g/cube dm] or [oz/cube ft]
In the English terminology uses the term "Wing Cube Loading" or "3D wing loading."
The numerical values calculated over imperial and metric units are approximately the same.
After reading the article, I hastened and calculated volume load some of our models. For comparison, I also included the area load divided by wing span. The biplane was wondering bearing area reduced by a factor 0.87 for the respect due to deterioration of the wing interaction.
We have a range of aircraft from about half a meter to 1.4 meters According to the wing loadings, the flying characteristics could not be reliably assumed. Eg. the VA Dragonfly is quite good and relaxed yet agile aircraft - WL is 23.8, while totally unmanageable for a beginner Mini Bee has WL 20.1.
But the Wing Cube Loading (WCL) works fantastically.
All our easily controllable aircraft (regardless of range) have WCL from 3.3 to approximately 6. The coolest Parastar has WCL 3.3. Somewhat difficult to piloting a tiny Champ with Mark 6.1. The vast quickie with difficult piloting - Mini Bee, especially with the original version of the wing (WCL = 12,3). With the wing from Multiplex Fox minigleder WCL is 10.8 - actually piloting is a little easier, but still significantly more difficult than Champ.
For comparison I added to the table value for a real aircraft - B52 :).
Model Weight Wingspan Effective Wing Wing
Wing Loading Cube
[g] [mm] [dm2] [g/dm2] [g/dm3]
VA Dragonfly 570 1200 24,00 23,8 4,8
Čemech Parastar 420 1200 25,56 6,4 3,3
Fenix 80 216 800 11,00 19,8 6,0
SDM WildHavk 580 1380 27,00 21,5 4,1
VA Pitts S2-CX 828 1005 38,36 21,6 3,5
Telink Toro 900 500 900 24,95 20,0 4,0
Mini Bee 65 500 3,04 21,4 12,3
Mini Bee with wing
from MPX Fox 74 495 3,61 20,5 10,8
HobbyZone Champ 42 517 3,61 11,7 6,1
empty 83914000 56390 37161 2258 11,7
fully loaded 221353000 56390 37161 5957 30.9
Empirically determined normal value of WCL (applies almost exactly as for the calculation of the metric (dm g) as well as imperial (ft and oz)).
type of model WCL
Slow Models, Thermal Glider <4
Trainers, Parkflyer, 3D 5-7
Sports Models, Scale Acrobats 7-10
Sports Models and Scale Models 10-13
Warplanes, Racing Models > 13
Effective Wing Area
monoplane: actual area
biplane: the actual area * 0.87
monoplane: the actual wingspan
biplane: (Actual total span of both wings) * square root of (0.87)
Simple Web WCL Calculator: http://www.ef-uk.net/data/wcl.htm